Motor driven timer with cam operated buzzer construction

ABSTRACT

A compact motor driven timer for cooking stoves includes a dial plate carrying time markings with one or more hands rotatable relative thereto on a shaft rotatably mounted on a mechanism plate on which the dial plate is mounted. A plastic mechanism case encloses a gear train interconnecting a synchronous motor mounted on the case and the hand or hands. Shouldered portions of the case extend through the mechanism plate which has deformable ribs to hold the shouldered portions of the case and thereby the case itself in place. Screws extend through the case to secure it and the motor to the mechanism plate. The gear train includes one or more clutches to rotate an interval hand at different speeds. A buzzer arm is released to vibrate in the magnetic field of the motor at the end of the manually preset interval. Time indicating hands are also driven by the motor. The interval hand is concentrically mounted with the time indicating hands or is offset therefrom. A notch is provided in the mechanism case to hold the ends of the leads to the motor temporarily in position. The gear train also operates a range timer which includes contacts that are closed at the beginning of a variable time cycle to start a cooking operation at a preset time of day. The contacts are opened at the end of the preset time cycle. The range timer can be set for manual operation by manual closure of the contacts.

United States Patent Bassett et a1.

[541 MOTOR DRIVEN TIMER WITH CAM OPERATED BUZZER CONSTRUCTION Inventors:Ronald M. Bassett; Joseph F. Gluth,

both of Chicago, 111.

Assignee: P. R. Mallory 8: Co., Inc. Filed: May 14, 1971 Appl. No.:143,653

Related U.S. Application Data Continuation-impart of Ser. No. 817,500,April 18, 1969, abandoned, Division of Ser. No. 878,618, Nov. 21, 1969,Pat. No. 3,601,973.

US. Cl. ..200/38 FA, 200/35 R, 74/354 Int. Cl. ..H0lh 7/08, I-lOlh 43/10Field of Search ..74/3.5 4; 200/35 R, 38 FA;

References Cited UNITED STATES PATENTS [451 Sept. 26, 1972 PrimaryExaminer-J. R. Scott Attorney-Robert F. Meyer 5 7 ABSTRACT theshouldered portions of the case and thereby the case itself in place.Screws extend through the case to secure it and the motor to themechanism plate. The gear train includes one or more clutches to rotatean interval hand at different speeds. A buzzer arm is released tovibrate in the magnetic field of the motor at the end of the manuallypreset interval. Time indicating hands are also driven by the motor. Theinterval hand is concentrically mounted with the time indicating handsor is offset therefrom. A notch is provided in the mechanism case tohold the ends of the leads to the motor temporarily in position. Thegear train also operates a range timer which includes contacts that areclosed at the beginning of a variable time cycle to start a cookingoperation at a preset time of day. The contacts are opened at the end ofthe preset time cycle. The range timer can be. set for manual operationby manual closure of the contacts.

. 9 Claims, 30 Drawing Figures PAIENTEDsms I972 SHEET b 0F 8 'Hlllll IIIII II Hlll em 9) Q um, Nw

PATENTEnsmsmz 3.694.591

' sum 5 0F 8 PATENTEDSEPZB m2 SHEET 6 OF 8 MOTOR DRIVEN TIMER WITH CAMOPERATED BUZZER CONSTRUCTION This application is a continuation-in-partof application Ser. No. 817,500, filed Apr. 18, 1969, now abandoned, anda division of application Ser. No. 878,618, filed Nov. 21, 1969, nowU.S. Pat. No. 3,601,973.

This invention relates, generally, to motor driven timers for electricand gas ranges and the like. It has particular relation to intervaltimers capable also of continuously indicating time and to range timersfor controlling the cooking time of an oven. It is desirable to reducethe dimensions of such devices and to provide for facilitating theirassembly. Also it is desirable to arrange for the interval time hand tobe rotated at a relativelylow speed during the beginning of the majorportion of a relatively long interval,-such as a 4-hour interval, and ata relatively high speed during the minor final portion of the interval,such as the last quarter hour.

Accordingly, among the objects of this invention are: To provide acompact motor driven timer which indicates time and can be presetmanually to operate a signal atthe end of a preset interval and toeffect the beginning and duration of the energization of the oven of anelectric or gas range; to mount a dial plate on a mechanism plate towhich a plastic mechanism case is secured in a novel manner; to securethe mechanism case to the mechanism plate by deformable ribs thereoncooperating with interfitting shoulders on the mechanism case; .tosubsequently position a synchronous motor on the mechanism case and tosecure it and the mechanism case to the mechanism plate by screws; toprovide a gear train in the mechanism case for connecting thesynchronous motor to a rotatable shaft to' which the interval hand issecured for rotation relative to interval time markings on the dialplate and'also to time indicating hands rotatable relative to the shaftand to time markings on the dial plate; to include in the gear train aclutch to permit rotation of the intervalhand independently of the timeindicating hands; for operation of the interval hand at different speedsto employ in the gear train a relatively low speed high torque clutch incombination with a relatively high speed low torque clutch; to arrangefor the clutches to drive a cam at the different speeds; at the end ofthe preset interval to release a buzzer arm to vibrate in the magneticfield of the synchronous motor and provide a signal; to arrange forholding the ends of the leads to the synchronous motor in a notch in theplastic mechanism case; to locate the interval hand in offset relationto the time indicating hands; to provide for operating contacts betweenclosed and open positions to supply heat to an electric or gas oven; toclose the contacts at a preset time of day and for a preset number ofhours; and to close the contacts manually to permit operation of theoven independently of the timer control.

In the drawings:

FIG. 1 is a view, in front elevation, and at full scale of a motordriven timer in which this invention is embodied.

FIG. 2 is a top plan view of the motor driven timer shown in FIG. 1.

FIG 3 is a partial view, in rear elevation of the motor driven timershown in FIG. 1.

FIG. 4 is a rear view of the motor driven timer, the synchronous motorhaving been omitted to show more clearly how the mechanism case isindependently secured to the rear side of the mechanism plate and thecontact housing also having been omitted to show the rear side of theframe plate on which it is mounted.

FIGS. 5A-5B show an exploded view of the motor driven timer.

FIG. 6 is a view, taken generally along line 6-6 of FIG. 58 looking inthe direction of the arrows and shows a part of the mechanism caseprovided with a shouldered portion for interfitting with the mechanismplate to be secured thereto by a deformable rib.

FIG. 7 is a view taken generally along line 7--7 of FIG. 5B and lookingin the direction of the arrows to show another shouldered portion of themechanism case for interfitting with the mechanism plate and to be heldthereto by a deformable rib.

FIG. 8 is a horizontal sectional view at an enlarged scale looking inthe direction of the arrows and taken generally along line 8-8 of FIG. 4and shows the gear train mounted within the mechanism case.

FIG. 9 is an elevational view of the cam that is mounted on the intervalshaft.

FIG. 10 is an elevational view of the cam shown in FIG. 9 looking fromleft to right.

FIG. 11 is a view of the cam shown in FIG. 9 looking from the oppositeside.

FIG. 12 is an elevational view of the cam shown in FIG. 11 looking fromleft to right.

' FIG. 13 is an elevational view of the drive dog that is secured to theinterval shaft.

FIG. 14 is a view, in front elevation, of a modified form of the motordriven timer, without the range timer section in which the interval handand interval markings are offset from the time indicating hands and thetime indicating markings on the dial plate. I 7

FIG. 15 is a view, in rear elevation, of the motor driven timer shown inFIG. 14.

FIG. 16 shows a portion of the gear train that is employed in the motordriven timer shown in FIGS. 14 and 15.

FIG. 17 is a horizontal sectional view at an enlarged scale looking inthe direction of the arrows and taken generally along line 17-17 of FIG.4 and shows the gearing and related parts for the range timer section.

FIG. 18 is an elevational full scale view of the cover for the contacthousing.

FIG. 19 is a vertical elevational view at an enlarged scale takengenerally along line 19-19 of FIG. 2 and shows the cam of the rangetimer section in the manual position.

FIGS. 20 and 21 are views, similar to FIG. 19 in which the cam is shown,respectively, in the off" position and in the timed cooking position.

FIG. 22 is an elevational view of the contact operating plate.

FIG. 23 shows the gear train for the range timer section.

FIG. 24 is an elevational view at an enlarged scale of the contacthousing and contacts taken along line 24 24 of FIG. 2 and looking in thedirection of the arrows,

the cover having been omitted.

FIGS. 25, 26 and 27 are sectional views taken generally along lines;25-25, 2626 and 27-27 respectively, of FIG. 24.

FIG. 28 is a perspective view at an enlarged scale of the contact bar.

FIG. 29 is a perspective view at an enlarged scale of the contact slidewhich carries the contact bar.

In FIGS. 1 and SA-B the reference character designates, generally, amotor driven timer embodying this invention. It includes an elongatedmetallic dial plate 11 that is arranged to be viewed through a glass 12that is held in place by a rectangular escutcheon 13. Tabs 14 extendrearwardly from the escutcheon l3 and overlie a flange 15 on the dialplate 11 to hold the assembly together. Time markings 16 are imprintedon the dial plate 1 1 and with respect to them an hour hand 17, aminutehand 18 and a second hand 19 are arranged to rotate. concentricallywithin the time markings 16 interval markings 20 are imprinted on thedial plate 11 and with respect to them an interval hand 21 rotatablewith an interval shaft 22 is arranged to rotate.

It will be observed that the interval markings 20 extend from 0 to 4.The markings between 0 and the 15 minute mark are laid out over an angleof 90 while the markings from 15 minutes to 1 hour are laid out over anangle of 49. The angular spacing between the hour marks 1, 2, 3 and 4 is46. As will appear hereinafter provision is made for rotating theinterval hand 21 relatively slowly from the 4 hour marking to the 1 hourmarking. During the next 45 minutes the speed of the interval hand 21 isincreased slightly and finally during the last 15 minutes it rotates ata relatively high speed. This makes it possible to adjust accurately asetting of the interval hand 21 for a relatively short interval while itis possible to obtain an interval setting of 4 hours within the confinesof the interval markings 20.

A knob 23, secured to the end of the interval shaft 22 that projectsthrough the glass 12, permits manual adjustment of the interval hand 21to the desired interval mark. When the shaft 22 and knob 23 are movedinwardly, as will appear hereinafter, the setting of the hour hand 17and minute hand 18 to the correct time can be accomplished.

Mounted on the rear side of the dial plate 11 is a metallic adapterplate 25. As shown in FIGS. 8 and 17 tabs 26 extend forwardly from theadapter plate through notches 27 in the dial plate 11 and aroundopenings 28 therein for securing the adapter plate 25 to the dial plate11. The tabs 26 are turned over to secure the adapter plate 25 in place.Four tabs 26 are employed at each location only two being shown.

Lugs 29, FIG. 3, extend rearwardly from the adapter plate 25 forentering openings 30, FIG. 5A, in a rectangular metallic mechanism plate31 which is held in spaced relation to the rear side of the adapterplate 25.

A moulded plastic mechanism case 32 is mounted on the rear side of themechanism plate 31. The manner in which it is held in position tofacilitate assembly of the motor driven timer 10 is important. As shownin FIGS. 6 and 7 shouldered portions 33 and 34 are moulded integrallywith the opposite ends of the plastic mechanism case 32 and they arearranged to interfit with openings 35 and 36, FIGS. 3 and 5A in themechanism plate 31. After the plastic mechanism case 32 has beenpositioned on the mechanism plate 31 with the shouldered portions 33 and34 extending through the openings 35 and 36, ribs 37 and 38 extendingbetween the openings 35 and 36 and slots 39 and 40 in the mechanismplate 31 are deformed inwardly to overlie the shouldered portions 33 and34. In this manner the plastic mechanism case 32 is securely held inplace on the mechanism plate 31. Thus it is held-temporarily in positionuntil additional fastening means are employed for further securing themechanism case 32 to the mechanism plate 31.

After the mechanism plate 32 has been assembled in the manner described,a synchronous motor, indicated generally at 43, is mounted on the rearside of the plastic mechanism case 32. The motor 43 can be constructedas disclosed in Svarnias US. Pat. No. 3,350,589, issued Oct. 31, 1967.Ears 44 extend laterally from the bottom of the rectangular magneticfield structure 43 of the motor 43 and they are notched to receivescrews 45 which extend through the plastic mechanism case 32 and arethreaded into the mechanism plate 31. In this manner not only is themotor 43 held in position but also the mechanism case 32 is furthersecured to the mechanism plate 31.

The motor 43 is arranged to be energized from a suitable alternatingcurrent source. For this purpose leads 46, FIG. 3, are provided. Some ofthe insulation is removed from the ends 47 of the leads 46 and theprojecting flexible conductors, if allowed to swing freely, mightscratch the motor driven timer 10 or adjacent ones on an assembly line.In order to prevent this, a slot 48 is moulded into the rear side of theplastic mechanism case 32 and, as shown in FIG. 3, the ends 47 of theleads 46 are inserted in it. In this manner these ends 47 are heldcaptive until such time as they are required to be removed forconnection in an energizing circuit.

After the end of the interval'for which the interval hand 21 is set, itis desirable that an audible signal be given. For this purpose avibrator arm 49 is employed generally as disclosed in the Svarniaspatent above referred to. The vibrator arm 49 is pivoted on a shaft 50that extends rearwardly from the plastic mechanism case 32. A torsionspring 51 acts to bias the vibrator arm 49 in a counter-clockwisedirection, FIG. 3, toward an extension 52 of the magnetic fieldstructure 43' of the motor 42. As shown in FIG. 4 a flange 53 dependsfrom the vibrator arm 49 and carries a cam follower pin 54 that extendsinto a groove 55, FIG. 9, of a cam that is indicated, generally, at 56.The cam 56 is secured to the inner end of the interval shaft 22 and isarranged to be driven in a manner to be described. An adjusting screw57, which extends through the vibrator arm 49, is employed for adjustingthe tension of the spring 51 and thus the frequency of the soundgenerated by the vibrator arm 59 when it is released.

As shown in FIGS. SB-and 8, a shaft 59 extends forwardly from the motor43. It is driven through a reduction gear train by the motor 43 at aspeed of 1 RPM. The shaft 59 is journaled in a bearing 60 that issecured to the flat bottom portion of the magnetic field structure 43'of the motor 43. The shaft 59 extends through a clearance opening 61 ina rear wall 62 of the plastic mechanism case 32. At its forward end theshaft 59 carries a pinion 63 which has a splined connection 64 with agear 65 that is journaled in the mechanism plate 31 and between it andthe adapter plate 25. The gear 65 meshes with a gear 66 that is securedto a second hand sleeve 67 which extends through the opening 28 in thedial plate 11 and on which the second hand 19 is mounted for rotationtherewith.

Also as shown in FIG. 8 the pinion 63 meshes with a gear 68 that isrotatably mounted on a stub shaft 69 that is carried by an embossmentformed integrally with the front side of the rear wall 62. Rotatabletogether with the gear 68 is a pinion 70 which drives a gear 71 that issecured to a pinion 72. The pinion 72 is fast on a shaft 73 one end ofwhich is journaled in the mechanism plate 31 while the other end isjournaled in the rear wall 62 of the plastic mechanism case 32. Thepinion 72 meshes with a gear 74 that is rotatable with respect to aminute sleeve 75 which is journaled on the interval shaft 22 and towhich the minute hand 18 is secured for rotation therewith. In order topermit setting of the time in the manner previously described, adiaphragm time set clutch 76 is secured to the minute sleeve 75 andfrictionally engages the juxtaposed surface of the gear 74. Thus, fortime setting purposes, the gear 74 remains stationary while the minutesleeve 75 is rotated for setting the correct time.

A pinion 78, integral with the minute sleeve 75, drives a gear 79 which,together with a pinion 80, is rotatably mounted on the shaft 73. Thepinion 80 drives a gear 81 that is secured to an hour sleeve 82 which isjournalled on the minute sleeve 75 within the mechanism plate 31. Thehour hand 17 is mounted on the hour sleeve 82 for rotation therewith. Itwill be noted that the second hand sleeve 67 is journaled on the hoursleeve 82.

Normally the interval shaft 22 is held in its outermost position by acoil compression spring 83 which reacts between the rear wall 62 of theplastic mechanism case 32 and the rear side of a drive dog 84, FIG. 13,which is secured to the interval shaft 22. The function of the drive dog84 will be described presently. The inner end 85 of the interval shaft22 is journaled at 86 in the rear wall 62 of the plastic mechanism case32. Rearwardly extending teeth 87 are provided on the outer end of theinterval shaft 22 for engaging slots 88 in the forward end of the minutesleeve 75. When it is desired to set thetime, the knob 23 and theinterval shaft 22 are moved inwardly to bring the teeth 87 intoengagement with the slots 88. Then, on rotation of the knob 23, theminute sleeve 75 is rotated and, through the gear train including thepinion 76, gear 79, pinion 80 and gear 81, the hour sleeve 82 also isrotated to rotate the minute hand 18 and hour hand 17 to the correcttime indication with respect to the time markings 16. The drive dog 84is slidably located in a correspondingly shaped slot 89, FIG. 9, in thecam 56 and provides a driving connection between the interval shaft 22and the cam 56 regardless of whether the interval shaft 22 is in theposition shown in FIG. 8 or is in the time setting position justdescribed in which the coil spring 83 is compressed.

As pointed out above, provision is made for rotating the interval hand21 and the interval shaft 22 at a relatively low speed for a majorportion of the presettable time interval and then to increase this speedof rotation during the last or minor portion of the interval in order tomake it possible to set accurately the position of the interval hand 21during this remaining interval. For this purpose a relatively low speedhigh torque clutch, FIG. 8, is employed and it is indicated, generally,at 92. Also there is provided a relatively high speed low torque clutchthat is indicated, generally, at 93.

Therelatively low speed high torque clutch 92 comprises a shaft 94 thatis journaled at one end in the mechanism plate 31 and at the other endin the rear wall 62 of the plastic mechanism case 32. A hub 95 issecured to the shaft 94 for rotation therewith and it carries a gear 96that is driven by a gear 97 which is secured to and rotates with theminute sleeve 75. A coil compression spring 98 reacts between the gear96 and a bushing 99 which is slidable on the shaft 94 and has frictionalengagement with one side of a pinion 100 the other side of whichfrictionally engages a flange 101 that is integral with the shaft 94.The pinion 100 is arranged to have driving engagement with gear teeth102 along the periphery of the cam 56.

The relatively high speed low torque clutch 93, FIG. 8, includes theshaft 73 previously described. Also it includes the gear 71 which issecured to the pinion 72 that, in turn, is secured to the shaft 73 androtates therewith. A washer 105 bears against the pinion 72 at one side.A coil compression spring 106 reacts between it and a washer 107 whichoverlies an annular flange 108 that extends inwardly from a pinion 109which is rotatable on shaft 73. A washer 110 on the other side of theflange 108 bears against a flange 111 that is integral with the shaft73. The teeth of the pinion 109 are arranged to engage the gear teeth102 on the cam 56.

It will be observed in FIG. 10 that the gear teeth 102 are partiallyomitted at 112. The purpose of this is to bypass the teeth on the pinion109 of the high speed clutch 93 during a portion of the revolution ofthe cam 56. The teeth 102 are omitted entirely as indicated at 113 fromanother portion of the periphery of the cam 56 in order to provide asection of the cam 56 that is not engaged by the teeth of either thepinion 100 of the low speed clutch 92 or the teeth of the pinion 109 ofthe high speed clutch 93. It is only during the presettable intervalthat the cam 56 and the interval shaft 22 are rotated. Otherwise theyremain stationary in the off position of the interval hand 21.

In order to facilitate engagement between the teeth of the high speedpinion 109 and the teeth 102 on the cam 56, as shown in FIG. 12, theteeth 102 increase in length from a minimum length. indicated at 114gradually to the full length. During the interval between the one hourmark and the 15 minute mark, both of the pinions 100 and 109 engage theteeth 102 on the cam 56. However, because the low speed clutch 92, dueto the tension of the spring 98, is capable of exerting a higher drivingtorque than is the high speed clutch 93 with a correspondingly weakerspring 106, the drive is essentially at the relatively low speed untilthe cam 56 is rotated to disengage the last tooth 115, FIG. 10, from thepinion 100, whereupon the drive is entirely through the high speedclutch 93 for the last 15 minutes of the interval.

During the presettable interval the cam 56 is rotated in acounter-clockwise direction as indicated byarrow 116 in FIG. 9 with thecam follower pin 54 remaining in the groove 55 and holding the vibratorarm 49 in the inoperative position. At the end of the presettableinterval, the cam 56 rotates relative to the cam follower pin .54 untilit drops into a relatively deep notch 117 as shown by a broken line.This releases the vibrator arm 49 and it is then free to vibrate in thealternating magnetic field of the synchronous motor 43. At this time theteeth 102 are not engaged by the teeth of the pinion 109 and the cam 56remains motionless while the vibrator arm 49 continues to vibrate. Inorder to stop vibration of the arm 49, the knob 23 and the intervalshaft 22 are rotated to bring the cam follower pin 54, shown by a brokenline, into a relatively shallow notch 118. This lifts the vibrator arm49 to the inoperative position and facilitates stopping the cam 56 inthe off" position which is indicated by the interval hand 21 registeringwith this indication on the interval markings 21, FIG. 1.

In those instances where it is desired to operate the interval shaft 22and the interval hand 21 at the same speed throughout the entireinterval, for example through an interval of 60 minutes instead of the 4hour interval indicated by the interval markings 20, then the relativelylow speed high torque clutch 92 is omitted and the cam 56 is modified toprovide the teeth 102 along its periphery, except for a relatively shortspan in which the teeth are omitted which corresponds to the end of theinterval and to the off position. With such a modification the intervalmarkings 20 are appropriately changed, for example to indicate a 60minute interval over the span of the 4 hour interval markings.

In FIG. 14 there is indicated, generally, at a modified motor driventimer which employs many of the elements of the motor driven timer 10previously described. Accordingly, where the same elements are used, thesame reference characters apply. In FIG. 14 it will be observed that theinterval markings 20', instead of being concentric with the timemarkings 16, are spaced or offset therefrom so as to be displayedseparately. Here the interval markings are from O to 60 minutes. In thisembodiment the interval hand 21 is mounted on an interval shaft 22',FIG. 16, while the time indicating hands 17, 18 and 19 are mounted on ashaft which is the same as the interval shaft 22 previously described. Aknob 23' at the outer end of the offset interval shaft 22 permits thesetting of the interval hand 21 to the desired position relative to theinterval markings 20.

In FIG. it will be noted that an extension 121 is secured to thevibrator arm 49 and that it carries at its distal end an upstandingflange 122 from which a cam follower 123 extends laterally to cooperatewith an interval cam surface 124, FIG. 16, on a cam 125 that is securedto the interval shaft 22 and rotates therewith. The cam 125 has teeth126 along its periphery except for a section 126' where they are omittedto correspond to the end of the interval and permit operation of themotor driven timer 10 for time keeping or other purposes withoutoperating the cam 125.

The cam 125 is driven by the synchronous motor 43. For this purpose apinion 127 engages the teeth 126 on the cam 125. The pinion 127 formsapart of a clutch that is indicated, generally, at 128. Its constructioncorresponds to the construction of the high speed clutch 93 previouslydescribed. The clutch 128 includes a gear 129 which is driven throughidler gears 130 and 131 from the gear 71 which is driven by the motor 43from the pinion 63 through the gear 68 and the pinion 70 as previouslydescribed.

When the interval shaft 22' and interval hand 21 are set to thepredetermined mark of the interval markings 20, the cam is rotated in aclockwise direction as indicated by arrow 132 until, at the end of thepreset interval, the cam follower pin 123 drops or moves outwardly intoa relatively deep notch 133 as shown by a broken line. It is biased tothis position by the torsion spring 51, previously described, and by acoil tension spring 134 which is secured at its lower end to theextension 121 and is fastened at its upper end over a tab 135 which isstruck from a plate 136 that overlies the cam 125 and is secured to themechanism plate 31. When the cam follower 123 is positioned in therelatively deep notch 133 in the cam 125, the vibrator arm 49 isreleased and it vibrates to indicate by a buzzing sound that the end ofthe preset interval has arrived. Then the knob 23 and the interval shaft22' are rotated manually in a clockwise direction to remove the camfollower pin 123 from the relatively deep notch 133 and to cause it tointerfit with a relatively shallow notch 137 along the internal camsurface 124, as shown by the broken line, and against a stop pin 138which prevents further rotation of the cam 125 in the clockwisedirection as viewed in FIG. 16.

Advantage is taken of the provision of the synchronous motor 43 andassociated gear train driven thereby for controlling the operation ofthe interval timer previously described to extend the utility of thismechanism for operating a range timer that is indicated, generally, at141 in FIGS. l-4, 5A-B. Here it will be observed that the dial plate 11carries start time markings 142 with respect to which a start time band143 rotates. The start time hand 143 is mounted on a start time shaft144 which can be preset manually by a knob 145 that extends forwardly ofthe glass 12.

The dial plate 11 also has cook hours markings 146 thereon andassociated therewith is an OFF position 147 and a MAN or manual position148. A cook hours hand 149 is arranged to rotate relative to tliesemarkings and is mounted for rotation with a cook hours shaft 150 havinga knob 151 at its outer end to permit manual presetting.

In FIG. 17 it will be observed that the start time shaft 144 extendsthrough an opening 28 in the adapter plate 25 and that it comprises apart of a start time assembly that is indicated, generally, at 154. Thestart time shaft 144 is endwise slidable through a sleeve 155 and isthereby rotatably mounted intermediate its ends. The sleeve 155 ismounted in an opening 156 that is formed at the base of a deformedsection 157 of the mechanism plate 31. Rotatably mounted on the sleeve155 is a gear 158 that is referred to in the claims as a first gear. Thegear 158 has a lug 159 struck therefrom for entering an opening 160 in agear 161 which is referred to in the claims as a second gear. The gear161 is rotatable with an annular operating member 162 which is securedat a knurled section 163 for rotation with the start time shaft 144. Theannular operating member 162 has a counterbore 164 for receiving a coilcompression spring 165 that reacts between the bottom of the counterbore164 and a fiat section 166 of a friction spring 167 with which aninturned tang 168 on a metallic frame plate 169 cooperates to preventturning about the start time shaft 144 which extends through the flatsection 166..As will appear hereinafter, the start time shaft 144 isarranged to be moved inwardly against the coil compression spring 165for the purpose of setting the start time by positioning the start timehand 143 at the desired time with respect to the start time markings142. When the start time shaft 144 is moved inwardly to position thegear 161, as shown by broken-lines, it is desirable that provision bemade for preventing rotation of the start time shaft 144 and the gear161. It is for this purpose that the friction spring 167 is employed andit is arranged to have frictional contact engagement with some of theteeth 170 along the periphery of the gear 161. When the gear 161 isshifted to the broken line position, it is located slightly past thedistal end of the lug 159 and then it can be rotated out of registrywith the opening 160. Upon release of the manual force moving the starttime shaft 144 inwardly against the biasing action of the coilcompression spring 165, the latter causes the face of the gear 161 toengage the distal end of the lug 159 to hold the start time shaft 144 inthe depressed position until the gear 158 is rotated to again positionthe lug 159 in registry with the opening 160 which occurs at thebeginning of the cook hours cycle. At its inner end the start time shaft144 is rotatably and slidably mountedin a bearing opening 171 in themetallic frame plate 169.

As shown more clearly in FIG. B the metallic frame plate 169 includesintegral forwardly extending walls 173 and 174 having lugs 175 alongtheir distal edges for entering suitable openings in the metallicmechanism plate 31. The lugs 175 are twisted slightly after passingthrough the mechanism plate 31 to hold the metallic frame plate 169securely in position thereon.

Again referring to FIG. 17 it will be noted that the gear 158 is drivenfrom the gear train that is driven by the motor 43. The gear trainincludes a gear 176 the teeth of which mesh with the teeth on theperiphery of the gear 158. Integral with the gear 176 is a gear 177 theteeth of which mesh with the teeth of the gear 81 previously describedwhich rotates at a speed of one revolution in 12 hours. A stub shaft 178extends from one side of the gear 176 into a bearing opening 179 that ismolded in an embossment 180 which forms a part of the molded plasticmechanism case 32. A stub shaft 181 extends from the other side of thegear 177 through a bearing opening 182 in the metallic mechanism plate31. In this manner, as long as the synchronous motor 43 is energized,the gear 158 is continuously driven. When the lug 159 registers with theopening 160 in the gear 161, the start time shaft 144 is continuouslydriven so that the start time hand 143 also indicates the time of day asdoes the hour hand 17.

In FIG. 17 it will be noted that the cook hours shaft 150 extendsthrough an opening 28 in the metallic adapter plate 25. It forms a partof a cook hours assembly that is indicated, generally, at 185.Intermediate its ends the cook hours shaft 150 is journaled in a bearingopening 186 that is located in the metallic mechanism plate 31. At itsinner end the cook hours shaft 150 is journaled in a bearing opening 187in the metallic frame plate 69. A hub 188 is pressed onto knurling 189on the cook hours shaft 150 to rotate therewith. A cam 190, FIGS. 5B, 19and 23, is secured to the hub 188 and thus it rotates conjointly withthe cook hours shaft 150. The cam 190 is arranged to move a cam followerpin 191 the mounting of which will be described presently. The camfollower pin 191 is biased toward a periphery of the cam 190 whichincludes a notch 192. When the pin 191 engages the notch 192, the cookhours hand 149 registers with the MAN" position 148 along the cook hoursmarkings 146. The periphery of the cam 190 also includes a recessedsection 193, FIG. 20. When the recessed section 193 is engaged by thecam follower pin 191, the cook hours band 149 registers with the OFFposition 147 along the cook hours markings 146. The periphery of the cam190 also includes as a major portion a circular section 194, FIG. 21,which is engaged by the cam follower pin 191 during the cook hoursperiod. A stop shoulder 194' at one end of the circular section 194 isengaged by the cam follower pin 191 to prevent further rotation of thecook hours shaft past the 6-hour marking.

Adjacent the cam and rotatable therewith and with the cook hours shaft150 is a cook hours gear 195. As shown more clearly in FIG. 23, gearteeth 196 are provided along a major portion of the periphery of thecook hours gear 195. They are omitted along a minor portion as indicatedat 197. A somewhat flexible driving connection is provided between thecam 190 and the cook hours gear 195 in order to facilitate drivingengagement with the gear teeth 196. For this purpose a connecting pin198, FIG. 17, is secured at 199 to the cam 190. The connecting pin 198has a reduced diameter end portion 200 which projects through a shortradial slot 201 in the cook hours gear 195. A tapered end 202 of a hub203 projects through an opening 204 in the cook hours gear 195 and alsoprojects into an opening 205 in the hub 188. A coil compression spring206 biases the hub 203 in the position shown in FIG. 17. At one end itreacts against the hub 203 and at the other end against a washer 207which is located in an annular groove 208 adjacent the bearing opening186 in the mechanism plate 31.

Driving engagement with the teeth 196 along the major portion of thecook hours gear 195 is had by a gear 213 which is secured by a knurledsection 214 to a shaft 215. One end of the shaft 215 is journaled in abearing opening 216 in the mechanism plate 31. At its other end theshaft 215 is journaled in a bearing opening 217 in the metallic frameplate 169. It is desirable to provide a slip type of drive for thegear213. For this purpose a gear 218 is rotatably mounted on the shaft215. Interposed between it and the adjacent surface of the gear 213 is afriction washer 219. A coil compression spring 220 reacts against theother side of the gear 218. The spring 220 is located in a counterbore221 in the gear 218. At one end the spring 220 bears against a washer222 at the base of the counterbore 221. The other end of the spring 220bears against a washer 223 adjacent a flange 224 which is formedintegrally with the shaft 215. The gear 218 is arranged to be driven bythe gear 161 when it returns from its position shown by broken lines inFIG. 17 to the full line position. The gear 218 has teeth 225 which areengaged by the teeth 170 on the gear 161. To facilitate this engagementthe teeth 225 are beveled as indicated at 226.

When the start time shaft 144 is moved inwardly, accompanied bycorresponding movement of the annular operating member 162, a convex endportion 229 of the operating member 162 engages an inclined surface 230,FIG. 22, that is provided by a shoulder member 231 which is formedintegrally with a slidable contact operating plate which is indicated,generally, at 232. This movement of the contact operating plate 232 oninward movement of the annular operating member 162 is against thebiasing action of a hairpin spring 233, FIG. 19. The hairpin spring 233has a central convolution located around a lug 234 that extends from andis formed integrally with a control plate 235 which is slidably mountedon the contact operating plate 232. One arm 236 of the hairpin spring233 extends through an opening 237 in the shoulder member 231. The otherarm 238 extends through arr-opening 239 in a lug 240 which is struckfrom and is formed integrally with the control plate 235. In order toreduce frictional engagement between the plates 232 and 235 the latterhas dimples 241 formed therein which permit only limited frictionalcontact engagement therebetween. Limited frictional contact engagementbetween the contact operating plate 232 and the juxtaposed surface ofthe metallic frame plate 169 is obtained through the provision in thelatter of an elongated shoulder 242, FIG. 5B and dimples 243. In orderto guide the plates 232 and 235 for translatory movement relative to themetallic frame plate 169, the latter has a pin 244 extending therefromthrough a slot 245 in the contact operating plate 232 and through a slot246 in the control plate 235. i

As shown in FIG. 17 the cam follower pin 191 extends through and issecured for movement to the control plate 235. Thus the position of thecontrol plate 235 depends upon the position of the cam follower pin 191with respect to the cam 190. A head portion 247 is formed integrallywith the cam follower pin 191 and it extends through a slot 248 in thecontact operating plate 232 and through a slot 249 in the metallic frameplate 169.

. The cook hours shaft 150 and the shaft2l5 extend through both of theplates 232 and 235. As shown in FIGS. 17, 19 and 22, a slot 250 in thecontact operating plate 132 has the inner end of the cook hours shaft150 extending therethrough. Overlying the slot 250 is a slot 251 in thecontrol plate 235. The shaft 215 extends through a slot 252 in thecontact operating plate 232 and through an overlying slot 253 in thecontrol plate 235.

As shown in FIGS. 19, 20 and 21 clearance openings 256 are formed in thecontrol plate 235 for receiving therethrough operating arms 257 fromplastic contact slides, one of which is indicated at 258 in FIG. 29. Theoperating arms 257 also extend through openings 259 in the contactoperating plate 232 which underlie the clearance openings 256. The ends260 of the. openings 259 engage one side 257' of each of the arms 257for controlling the positions of the contact slides 258. The operatingarms 257 from the contact slides 258 extend through slots 261, FIG. 5Bin the base of a plastic contact housing that is indicated, generally,at 262.

FIGS. 24-26 show in more detail the construction of the plastic contacthousing 262 and parts associated therewith. Here it will be observedthat pairs of stationary contacts 263 and 264 are suitably mounted inthe contact housing 262 along one side and additional pairs 265 and 266of stationary contacts are suitably located on the other side. Bridgingcontact members 267 and 268 are arranged to interconnect the contacts263 and 264, respectively, or the contacts 265 and 266, respectively,when they are moved from the positions as shown in FIG. 24. It will beunderstood that only a single pair of stationary contacts can beemployed in conjunction with a single bridging contact member. However,for purposes of illustration several pairs are shown together with apair of bridging contact members 267 and 268. One of the bridgingcontact members 267 is illustrated in FIG. 28. It is arranged to bepositioned in a slot 269 in the respective contact slide 258.

As shown in FIG. 27 the bridging contact member 268 is arranged to bebiased in one direction by a relatively weak spring 270 which reactsbetween the bridging contact member 268 and one end of the slot 269. Itis arranged to be biased in the opposite direction by a relativelystrong spring 271 which reacts between one end of the slot 261 and oneside of the contact slide 258. It will be understood that the relativelystrong springs 271 bias the operating arms 257 against the ends 260 ofthe openings 259 in the contact operating plate 232 and through thehairpin spring 233 hold the cam follower pin 191 against the cam surfaceof the cam 190.

The pairs of stationary contacts 263-264 and 265-266 are held in placeby a plastic cover 272, FIGS. 18, 25, 26 and 27. The plastic cover 272has rectangular shoulders 273 on its underside which, as shown in FIG.25, are arranged to overlie a shank 274 of each of the stationarycontacts to hold the same securely in place. A grounding plate 275overlies the cover 272 and it and the cover 272 are held in place on theplastic contact housing 262 by bolts 276.

In order to locate properly the plastic contact housing 262 on the rearside of the metallic frame plate 169, the former is provided withintegrally formed dowel pins 279, FIG. 19, which extend through slots280 formed in the frame plate 169. At the other end of the plasticcontact housing 262 there is integrally formed a hollow dowel pin 281which extends through a corresponding opening 282 in the metallic frameplate 169.

For securing the plastic contact housing 262 to the metallic frame plate169, the former is provided with an elongated lug 283, FIG. 5B, that isarranged to extend laterally through a slot 284 in an upstruck lug 285from the metallic frame plate 169. At its other end the plastic contacthousing 262 has an elongated slot 286 molded therein for receiving a lug287, FIG. 3, which is struck from the metallic frame plate 169.

In operation, when the range timer section 141 is not preset, the cookhours hand 149 usually is left in registry with the MAN indication. Theposition of the cam for the manual operation is as shown in FIG. 19where the cam follower pin 191 engages the notch 192. In this positionthe bridging contact members 267 and 268 are biased into engagement,respectively, with the pairs of stationary contact 265 and 266 by thesprings 270 or in their alternate positions from those shown in FIG. 24and the springs 271 are further stressed. The bridging contact members267 are shown in FIG. 24 in their OFF positions biased into contactengagement by the springs 271 with the pairs of stationary contacts 263and 264 which corresponds to the position of the cam follower pin.l91 inthe recessed section 193 of the cam 190 as shownin FIG. 20. In thisposition of the cam 190 the cook hours hand 149 registers with the OFFposition 147. To set the number of cook hours, the knob 151, FIG. 1 isrotated in a counter-clockwise direction until the cook hours hand 149is set to the number of cook hours desired. This is accompanied byrotation of the cam 190 to a position, such as that illustrated in FIG.21, where the cam follower pin 191 engages the circular section 194 ofthe periphery of the cam 190. The position of the contact operatingplate 232 is the same here as for its position when the cam follower pin191 engages the notch 192. Accordingly, during the cook hours period,the bridging contact. members 267 and 268 are in engagement with thepairs of stationary contacts 265 and 266 respectively, it. beingunderstood that only a single bridging contact 267 and single pair ofstationary contacts 265 can be employed for controlling the completionof a single circuit.

The start time is set by moving the start time shaft 144 inwardly bymanually depressing the knob 145. This action is accompanied by movementof the gear 161, FIG. 17, to the position shown by broken lines andengagement of the convex end portion 229 of the annular operating member162 with the inclined surface 230 of the shoulder member 231 on thecontact operating plate 232. There is a corresponding shifting in themovement, indicated by arrow 288, of the contact operating plate 232transmitted through the hairpin spring 233 which is accompanied bymovement of the bridging contact members 267 and 268 to the positionsshown in FIG. 24, this movement of the contact members 267 and 268 beingeffected-by expansion of the coil compression. springs 271. There is acorresponding stressing of the hairpin spring 233.

When the start time shaft 144 was moved inwardly to effect acorresponding inward movement of the gear 161 and rotation to thedesired start time, the driving connection provided by the lug 159 tothe gear 161 is interrupted and the spring 165 holds the gear 161against the distal end of the lug 159. When the time driven gear 158 isrotated to such position that the lug 159 registers with the opening 160in the gear 161, the latter is biased to the position shownby full linesin FIG. 17 by the coil compression spring 165 and the teeth 170 of thegear 161 then slide over the beveled portions 226 to engage the teeth225 on the gear 218. The convex end portion 229 of the annular operatingmember 162 is withdrawn from the inclined surface 230 on the shouldermember 231 and the contact operating plate 232 is shifted to theposition shown in FIG. 21 under the biasing action of the hairpin spring233 against the biasing action of the springs 271. The bridging contactmembers 267 and 268 then engage stationary contacts 265 and 266 toenergize the oven and start the cook hours cycle. The gear 213 isrotated to drive the cook hours gear 195 which is accompanied byrotation of the cam 190 in a clockwise direction indicated by arrow 290,FIG. 21, from its position, such, as that shown here until, at the endof the cook hours cycle, the cam 190 will have been rotated to theposition shown in FIG. where the cam follower 191 engages the recessedsection in 193 of the cam 190. When this occurs the relatively strongsprings 271 shift the contact slides 258 and therewith the bridgingcontact members 267 and 268 to the OFF positions in FIG.

24 thereby opening the circuits through stationary contacts 265 and 266or at least one pair of these contacts to deenergize the oven or otherequipment under the control of the range timer section 141. At this timethe cook hours gear 195 has been rotated to such position that none ofthe gear teeth 196 is engaged by the gear 213 which continues to rotatewithout driving the gear 195 since that portion 197 of the cook hoursgear 195 having no teeth is opposite the gear 213. However, the

gear 213 continues to rotate along with gears 218, 161

and 158 with the start time hand 143 then occupying the same positionrelative to the start time markings 142 that the hour. hand 17 occupieswith respect to the time marking 16. For manual operation, the knob 151and cook hours shaft are rotated in a clockwise direction, indicated byarrow 291 in FIG. 19, to rotate the notch 192 on the cam into engagementwith the cam follower pin 191. The cook hours hand 149 then registerswith the MAN" marking 148.

In order to insure that the cam follower pin 191 is maintained inengagement with the surface of the cam 190 and particularly fully entersthe recessed section 193, coil tension springs 292, FIG. 19,interconnect ears'293 on the control plate 235 and one end of each ofthe walls 173 and 174 that extend forwardly from the frame plate 169.

What is claimed as new is:

l. A timer comprising:

a dial plate carrying time interval markings,

a mechanism plate mounting said dial plate,

an interval shaft rotatably mounted on said mechanism plate andextending therethrough and through said dial plate,

an interval hand on said interval shaft rotatable therewith relative tosaid time interval markings on said dial plate and manually settablewith said shaft to a predetermined interval,

a mechanism case mounted on the side of said mechanism plate away fromsaid dial plate,

an alternating current timing motor mounted on the side of saidmechanism case away from said mechanism plate and having a magneticfield structure,

a gear train having at least a part in said mechanism case andinterconnecting said motor and said interval shaft,

a buzzer arm mounted on said mechanism case and arranged to be vibratedby the magnetic field of said magnetic field structure,

a cam follower connected to said buzzer arm,

a cam on said interval shaft engaged by said cam follower for holdingsaid buzzer arm in nonoperating position with respect to said magneticfield until the end of the interval for which the timer is set,

a frame plate mounted on said mechanism plate in spaced relation theretoand endwise of said mechanism case,

contact means mounted on the side of said frame plate away from saidmechanism plate,

contact operating means mounted on the side of said frame plate towardsaid mechanism plate,

manually settable rotatable start time gear means mounted between saidmechanism plate and said frame plate including a start time shaftextending through said mechanism plate and said dial plate forcontrolling, in part, operation of said contact operating means,

manually settable rotatable cook hours gear means mounted between saidmechanism plate and said frame plate including a cook hours shaftextending through said mechanism plate and said dial plate forcontrolling, in part, operation of said contact operating means,

gearing interconnecting said start time gear means and said cook hoursgear means, and

gearing interconnecting said start time gear means and said gear trainfor shifting said contact means from one position to another position atthe start of a preset time cycle and vice versa at the end of said timecycle.

2. The timer according to claim 1 wherein:

an insulating contact housing is mounted on said frame plate, and

said contact means includes:

a pair of stationary contacts mounted on said contact housing, and

a-contact bar bodily movable on said housing into and out of bridgingengagement with said stationary contacts.

3. The timer according to claim 2 wherein:

an insulating contact slide is movable in a slot in said contacthousing, carries said contact bar and has an arm extending through saidframe plate into said contact operating means,

a relatively weak coil compression spring in said contact slide biasessaid contact bar against said contact slide, and i a relatively strongcoil compression spring in said ,slot biases said contact slide andthereby said contact bar out of said bridging engagement witli saidstationary contacts.

- 4. The timer according to claim 1 wherein said contact operating meansincludes:

a contact operating plate slidable on said frame plate, connected tosaid contact means, and shiftable by said start time means to move thesame to said other position, and

a control plate slidable on said contact operating plate, connectedthereto through spring means, and shiftable by said cook hours means tomove said contact means to said one position.

5. The timer according to claim 4 wherein said contact means includes:

a movable contact member, and

a contact spring biasing said contact member toward said other position,and

said spring means interconnecting said contact operating and controlplates is capable of moving said contact member toward said one positionagainst the biasing action of said contact spring.

6. The timer according to claim 4 wherein:

an inclined shoulder member is carried by said contact operating plate,

means support said start time shaft for endwise movement, and

an annular operating member on said start time shaft engages saidinclined shoulder member on endwise movement of said start time shaft toshift said contact operating plate to move said contact means to a firstgear is rotatably mounted on said start time shaft and is driven at aconstant speed by said motor through said gear train,

a second gear is secured to and rotates with said start time shaft,

a spring biases said start time shaft and said second gear toward saidfirst gear and said annular operating number away from said inclinedshoulder member, and

means provide a driving connection between said first and second gearswhen said first gear is rotated to the preset start time position at thestart of said preset time cycle.

8. The timer according to claim 4 wherein:

a cam follower is carried by said control plate, and

a cam is secured to and rotates-with said cook hours shaft and has a camsurface engaging said cam follower to shift said control plate betweensaid positions, said cam surface including a notch for holding saidcontrol plate with said contact means in said one position, a recessedsection permitting said control plate and said contact means to shift tosaid other position, and a circular section for holding said controlplate with said contact means in said one position.

9. The timer according to claim 7 wherein:

a cam follower is carried by said control plate,

a cam is secured to and rotates with said cook hours shaft and has a camsurface engaging said cam follower to shift said control plate betweensaid positions, said cam surface including a notch for holding saidcontrol plate with said contact means in said one position, a recessedsection permitting said control plate and said contact means to shift tosaid other position, and a circular section for holding said controlplate with said contact means in said one position,

a cook hours gear is secured to and rotates with said cook hours shaftand has gear teeth along a major portion of its periphery, and

gear means interconnect said cook hours gear and said second gear at thestart of said preset time cy cle.

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Pa t NO.3,694,591 D d September 26, 1972 lnven fls) Ronald M. Bassett, et, a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Oh the cover sheet in the Abstract, line 5-, "mounted" should readsupported Column 5, line 48, "76" should read 78 Signed and sealed this1st day of May 1973.

(SEAL) Attest:

EDWARD M.FLE'I'CHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents F ORM O-O50 (10-69) U,S. GOVERNMENT PRINTNG OFFICE: I9690-366-33;

UNITED STATES-PATENT OFFICE CERTIFICATE OF CORRECTION Patent NO.3,694,591 Dated September 26, 1972 Invento Ronald M. Bassett, et. al

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

On the cover sheet in the Abstract, line 5, "mounted" should readsupported Column 5, line 48, "76" should read 78 Signed and sealed this1st day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PO-IOSO (O-691 USCOMM-DC 60376-P69 n u.s. GOVERNMENTPRINTING OFFICE: 1959 O366-334;

1. A timer comprising: a dial plate carrying time interval markings, amechanism plate mounting said dial plate, an interval shaft rotatablymounted on said mechanism plate and extending therethrough and throughsaid dial plate, an interval hand on said interval shaft rotatabletherewith relative to said time interval markings on said dial plate andmanually settable with said shaft to a predetermined interval, amechanism case mounted on the side of said mechanism plate away fromsaid dial plate, an alternating current timing motor mounted on the sideof said mechanism case away from said mechanism plate and having amagnetic field structure, a gear train having at least a part in saidmechanism case and interconnecting said motor and said interval shaft, abuzzer arm mounted on said mechanism case and arranged to be vibrated bythe magnetic field of said magnetic field structure, a cam followerconnected to said buzzer arm, a cam on said interval shaft engaged bysaid cam follower for holding said buzzer arm in nonoperating positionwith respect to said magnetic field until the end of the interval forwhich the timer is set, a frame plate mounted on said mechanism plate inspaced relation thereto and endwise of said mechanism case, contactmeans mounted on the side of said frame plate away from said mechanismplate, contact operating means mounted on the side of said frame platetoward said mechanism plate, manually settable rotatable start time gearmeans mounted between said mechanism plate and said frame plateincluding a start time shaft extending through said mechanism plate andsaid dial plate for controlling, in part, operation of said contactoperating means, manually settable rotatable cook hours gear meansmounted between said mechanism plate and said frame plate including acook hours shaft extending through said mechanism plate and said dialplate for controlling, in part, operation of said contact operatingmeans, gearing interconnecting said start time gear means and said cookhours gear means, and gearing interconnecting said start time gear meansand said gear train for shifting said contact means from one position toanother position at the start of a preset time cycle and vice versa atthe end of said time cycle.
 2. The timer according to claim 1 wherein:an insulating contact housing is mounted on said frame plate, and saidcontact means includes: a pair of stationary contacts mounted on saidcontact housing, and a contact bar bodily movable on said housing intoand out of bridging engagement with said stationary contacts.
 3. Thetimer according to claim 2 wherein: an insulating contact slide ismovable in a slot in said contact housing, carries said contact bar andhas an arm extending through said frame plate into said contactoperating means, a relatively weak coil compression spring in saidcontact slide biases said contact bar against said contact slide, and arelatively strong coil compression spring in said slot biases saidcontact slide and thereby said contact bar out of said bridgingengagement with said stationary contacts.
 4. The timer according toclaim 1 wherein said contact operating means includes: a contactoperating plate slidable on said frame plate, connected to said contactmeans, and shiftable by said start time means to move the same to saidother position, and a control plate slidable on said contact operatingplate, connected thereto through spring means, and shiftable by saidcook hours means to move said contact means to said one position.
 5. Thetimer according to claim 4 wherein said contact means includes: amovable contact member, and a contact spring biasing said contact membertoward said other position, and said spring means interconnecting saidcontact operating and control plates is capable of moving said contaCtmember toward said one position against the biasing action of saidcontact spring.
 6. The timer according to claim 4 wherein: an inclinedshoulder member is carried by said contact operating plate, meanssupport said start time shaft for endwise movement, and an annularoperating member on said start time shaft engages said inclined shouldermember on endwise movement of said start time shaft to shift saidcontact operating plate to move said contact means to said otherposition.
 7. The timer according to claim 6 wherein: a first gear isrotatably mounted on said start time shaft and is driven at a constantspeed by said motor through said gear train, a second gear is secured toand rotates with said start time shaft, a spring biases said start timeshaft and said second gear toward said first gear and said annularoperating number away from said inclined shoulder member, and meansprovide a driving connection between said first and second gears whensaid first gear is rotated to the preset start time position at thestart of said preset time cycle.
 8. The timer according to claim 4wherein: a cam follower is carried by said control plate, and a cam issecured to and rotates with said cook hours shaft and has a cam surfaceengaging said cam follower to shift said control plate between saidpositions, said cam surface including a notch for holding said controlplate with said contact means in said one position, a recessed sectionpermitting said control plate and said contact means to shift to saidother position, and a circular section for holding said control platewith said contact means in said one position.
 9. The timer according toclaim 7 wherein: a cam follower is carried by said control plate, a camis secured to and rotates with said cook hours shaft and has a camsurface engaging said cam follower to shift said control plate betweensaid positions, said cam surface including a notch for holding saidcontrol plate with said contact means in said one position, a recessedsection permitting said control plate and said contact means to shift tosaid other position, and a circular section for holding said controlplate with said contact means in said one position, a cook hours gear issecured to and rotates with said cook hours shaft and has gear teethalong a major portion of its periphery, and gear means interconnect saidcook hours gear and said second gear at the start of said preset timecycle.